Comment by frou_dh

To me the charming thing about Emacs is how introspective a program it is. This goes beyond all the documentation being built-in, and being able to redefine things on the fly. For instance, it's easy to define a keybinding that does "Take me to the source code of the command that's bound to the next keybinding I type". When you use that and land at a destination, it will probably be Elisp code, but in some cases will even be C code - it works either way.